Turbo charger selection and cam timing.

[Turbomad]

Hello everbody.
I'm currently building a toyota 20v turbo motor for a little tube frame sports sedan racer toyo starlet i have..
Motor specs are briefly, 7.5/1 comp, ceramic coated pistons, 20v head with extensive port work, stock spec cams, ex manifold is equal length feeding into a Garret T3-t4 series hybrid that I recently built.
I'm a little worried about compressor surge..
Turbo specs are To4b comp cover .6ar, 55mm 8blade comp wheel, plain bearing core, stock t3 stage 1 turbine shaft with 0.63ar exh housing, 32mm external 'wastegate'.

Motor does not need any low end but must have good top end as the g/box i have has reasonably close ratios.
Ie: don't need any positive manifold untill 4500-5000rpm.
Looking to run between 2 and 2.4 pressure ratio.
Anyone had any experience with this combination or something similar? Engine is fitted to 600kg vehicle. with 4.8 or 5.2/1 diff ratio.
Can anyone help out with inlet runner length, it will still be running the factory multi throttles with an undecided plenum volume.
Hoping to make over 400hp to make this combination work in my weight bracket, gotta beat the big cube brodies.
Sorry bout the long post but there are so many variables to consider....

 

[toytech]

I am working on a turbocharged 4agze myself, however I chose a Garrett gt2540r for my application my turbo supplier felt it will make full boost at 4800rpm, and it flows 44lb per min of air, so 400+ horsepower is attainable with decent spooling due to the smallish hot side and dual ball bearing center. Your Starlet sounds like it is going to be scary

 

[mister2]

hi,

funnily enough this is what im doing too (aw11 mr2, with turbo 20v, 4agze bottom end with T3 turbo) and to check for compressor surge i just ran the figures and check whereabouts it was operating on the compressor maps which if you have a look around the internet you should be able to find. try turbonetics or ray hall turbocharging.

as for the intake, i discarded the quad throttles and used a intake length of ~35cm which corresponded to around about 6000rpm on the second fundamental (i think, cant quite remember!). i couldnt find anything really pertinent to turbocharged intake plenum sizing so i went with 2x the swept capacity, i dont know if this is good/bad!

actually, i know i guy who has stuck one in a kp61 starlet, it was pretty mad!!

nick

 

[Turbomad]

Thanks for the help,
I've run quite a few different turbo setups,
A datsun 1200 coupe fitted with a z22 2.2L Nissan 'NAPS' engine running a 60 trim t3 with .48ar rear housing.
Was a great setup for road, had full manifold pressure of 13psi at 2800, and made about 300 horse anywhere above 4000.
VERY FUN road car.
Also had a relatively mild 4age 16v turbo in a starlet that ran a 50 trim t3 with .48 ar rear housing that was fairly effective, but I've now decided to completely reengineer the whole car and need about double what it was making before to be competitive..
I've run the math for my planned turbo system on the wild 20v and it's very borderline in the surge department.
Was hoping someone had tryed something similar...
Good to see there are other guys out there playing with Forced Fire....
Thanks for the feedback and i'll keep you posted.
PS: Toytech would you be willing to tell me what the A/R are on the gt 2540r you are going to be running are?

 

[toytech]

Sorry, .64 AR, also is available with a .84, but I wanted it to spool a little faster.